A next generation mobile wireless communication system generally provides a high speed multimedia service. For example, 3GPP LTE and LTE-Advanced are one of the next generation cellular communication standards, which create a new series of specifications for the new evolving radio-access technology. With the use of multimedia service becoming more widespread, wireless communication users' demand for faster, more reliable, and better multimedia is growing.
To accommodate such a growing demand, research to provide more efficient and improved service is taking place. In other words, various methods of improving data transmission are being researched, and in particular, ways to improve use of frequency resources are being explored.
Due to the increasing demand for higher throughput, the tendency of offloading cellular network traffic has received enormous attention, e.g., femto and other small cells. Increasing demand of offloading cellular traffic has attracted attention from most industrial partners to the D2D communication. The aim of D2D communication is pursuing this track to allow mobile terminals to transmit data to each other without, or with limited help from the infrastructure.
In order to efficiently utilizing spectrum, same frequency band is allowed to be shared by both cellular users and D2D devices. However, when the same subcarrier or frequency band is allocated for D2D communication and cellular communication at the same time, the interference to each other would highly degrade the communication quality for both of uplink cellular communication (“uplink” hereafter) and downlink cellular communication (“downlink” hereafter).
In view of the foregoing problem, there is a need to reduce the interference from D2D communication to cellular communication in both uplink and downlink, so as to effectively improve performance of a communication system comprising both the D2D communication and cellular communication.